1. Field of the Invention
The present invention relates to a power conversion controller, and more particularly to a high side controller capable of sensing input voltage and output voltage of a power conversion circuit to provide desirable performance.
2. Description of the Related Art
In the high side driver circuit of a general power conversion application, the positive end of an input voltage source is generally coupled to one end of the channel of a power transistor. When the power transistor is turned on by a control signal, the input power from the input voltage source will be transmitted through the power transistor to an inductor, and the potential difference between the other end of the channel of the power transistor and the negative end of the input voltage source will be approximately equal to the input voltage of the input voltage source. When the power transistor is turned off, the positive end of the input voltage source will be isolated by the power transistor, and, to keep the current continuity in the inductor, the potential difference between the other end of the channel of the power transistor and the negative end of the input voltage source will change polarity and amplitude accordingly.
To switch the power transistor, a high side controller is utilized to generate the control signal. As is often seen, the reference ground of the high side controller is coupled to the other end of the channel of the power transistor, so that a low voltage controller can be used to provide the control signal. However, as the potential difference between the other end of the channel of the power transistor and the negative end of the input voltage source varies in polarity and amplitude with time during switching operation, it is not easy to sense the input voltage of the input voltage source.
In view of this problem, the present invention proposes a mechanism for sensing input voltage and output voltage of a power conversion circuit via the negative end of an input voltage source, to provide desirable performance for the power conversion circuit.